The following calculation tool will answer this question by comparing the cost per kilowatt hour (kWh) PV electricity with your reference price. The tool offers two main options which may be selected by you. In case the PV electricity will be self-consumed by you as the plant operator, the PV electricity cost will be compared with your grid electricity price and the net savings are presented as main result. In case you supply the PV electricity to a nearby consumer, the contracted price will be compared with the PV electricity cost and the net-profit is presented as main result. In addition, some key economic figures for the project are shown below the main result on the right. The underlying excel tools can be downloaded on the bottom right. In order to adjust the calculations to your individual case you need to answer some key questions by adjusting the sliders below each chart. Your adjustments directly influence the PV electricity cost of the PV system which is compared with your reference price you enter in the box on the right.
If you have received an quote from a PV installer simply divide your total cost by the system size in kWp. Please make sure to include or exclude sales tax as a private individual or a company. Reference values: Typical residential systems cost between 1,300 - 1,500 €/kWp and commercial systems between 1,100 - 1,300 €/kWp.
In case you already received an offer from your local installer, you can find the irradiation at your location in his offer. Alternatively, you can find the irradiation values for your region on this website re.jrc.ec.europa.eu/pvgis/. Reference values: Irradiation in Southern Europe is between 1,300 - 1,800 and in Northern Europe 800 - 1,200 (kWh/sqm/year).
Typicall feed-in tariff support schemes established a common operating time of 20 years while quality modules come with warranties above 20 years and will operate up to 30 years. Reference value: 20 years are a commonly used and costs for replacing components with a shorter lifetime are already considered in the calculations.
The performance ratio is a technical figure mainly depending on the roof orientation, inclination and type of solar modules. This value should be provided in the offer from your local installer. Reference values: For south facing systems it ranges between 0.80 - 0.85.
Typical debt gearings (loans) for commercial PV investments are between 70-80% of the total cost depending on the risk involved. This usually requires a feed-in tariff as a fall back option in case the PV electricity cannot be self-consumed or supplied as expected. If a feed-in tariff is not available then the debt gearing depends on the overall solvency - credit rating - of the individual or company obtaining the loan. Reference value: Small private systems based on self-consumption are usually fully equity financed.
Individual interest rates for consumer loans or commercial loans apply if the system is based on self-consumption or a supply contract without a feed-in tariff as fall back option. Reference value: If the financing is based on a long term fixed feed-in tariff, interest rates could be as low as 2%.
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